gh-119786: [doc] broken link and typo fix in interpreter_definition.md (#125455)

Author: efimov-mikhail

InternalDocs/README.md

@@ -11,6 +11,8 @@ The core dev team attempts to keep this documentation up to date. If
 it is not, please report that through the
 [issue tracker](https://github.com/python/cpython/issues).
 
+Index:
+-----
 
 [Guide to the parser](parser.md)
 

Tools/cases_generator/interpreter_definition.md

@@ -74,7 +74,7 @@ We update it as the need arises.
 ### Syntax
 
 Each op definition has a kind, a name, a stack and instruction stream effect,
-and a piece of C code describing its semantics::
+and a piece of C code describing its semantics:
 
 ```
   file:
@@ -245,7 +245,8 @@ The same is true for all members of a pseudo instruction
 
 ## Examples
 
-(Another source of examples can be found in the [tests](test_generator.py).)
+(Another source of examples can be found in the
+[tests](https://github.com/python/cpython/blob/main/Lib/test/test_generated_cases.py).)
 
 Some examples: